scholarly journals Experimental study of impinging flow generated by synthetic jets actuators

2012 ◽  
Vol 25 ◽  
pp. 02013
Author(s):  
Michal Kotek ◽  
Václav Kopecký
Keyword(s):  
Experimental Study ◽  
Synthetic Jets ◽  
Impinging Flow

Impinging Jet Boiling of a Fluorinert Liquid on a Foil Heater Array

2000 ◽  
Vol 122 (2) ◽  
pp. 132-137 ◽  
Author(s):  
Wataru Nakayama ◽  
Masud Behnia ◽  
Hiroaki Mishima
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Flux ◽  
Thick Plate ◽  
Jet Impingement ◽  
Thermal Mass ◽  
Rapid Rise ◽  
Slot Nozzle ◽  
Transfer Behavior ◽  
Impinging Flow

An experimental study of forced convection in impinging flow, using fluorocarbon FX3250 and a simulated electronic chip, was performed. A test section consisting of a 35 mm long, 1 mm wide slot nozzle in a 2 mm thick plate offset 2 mm from the heat source was used. The simulated chip array consisted of five foil strip (4 mm wide) heaters, positioned with the center strip directly beneath the slot nozzle. The velocity of the coolant was varied from 0.53 to 5 m/s, and the subcooling in the range from 2 to 21 K. The experiments were conducted focusing on two cases. First, only the center strip was heated. Second, all the heaters were energized, and the strip-by-strip variations of heat transfer were measured. The critical heat flux (CHF) on the center strip, determined by sensing the onset of oscillations and subsequent rapid rise of foil temperatures, was found considerably lower than those predicted by the existing correlations. It is pointed out that the thermal mass of the test heater could be an important factor for the CHF. The heat transfer behavior of other strips showed channel-flow or jet-impingement mode depending on the strip location and the coolant flow rate. [S1043-7398(00)00202-4]

An Experimental Study of Impinging Synthetic Jets for Heat Transfer Augmentation

2015 ◽  
Vol 23 (03) ◽  
pp. 1550024 ◽  
Author(s):  
Omidreza Ghaffari ◽  
Muhammad Ikhlaq ◽  
Mehmet Arik
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Vertical Surface ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Coefficient Of Performance ◽  
Stroke Length ◽  
Cooling Performance ◽  
Circular Jets ◽  
Number Formula

According to recent trends in the field of miniature electronics, the need for compact cooling solutions compatible with very thin profiles and small footprint areas is inevitable. Impinging synthetic jets are recognized as a promising technique for cooling miniature surfaces like laptops, tablets, smart phones and slim TV systems. Effect of jet to cooled surface spacing is crucial in cooling performance as well as predicting Nusselt number for such spacing. An experimental study has been performed to investigate the cooling performance of two different synthetic jets actuated with piezoelectric actuators cooling over a vertical surface. Results showed that a major degradation of heat transfer when jets are close to the surface is occurred. Slot synthetic jets showed a better performance in terms of coefficient of performance (COP) than semi-confined circular jets for small jet to surface spacing. Later, a correlation is proposed for predicting Nu number for a semi-confined circular synthetic jet accounting the effects of Re number ([Formula: see text]), jet-to-surface spacing ([Formula: see text] and [Formula: see text]) and the stroke length ([Formula: see text] and [Formula: see text]). It is found that correlation can provide predictions with an [Formula: see text] value of over 98%.

Vortex Dynamics of Synthetic Jets: A Computational and Experimental Investigation

2010 ◽  
Author(s):  
Mehmet Arik ◽  
Yogen Utturkar
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Laser Doppler Anemometry ◽  
Computational Study ◽  
Fluid Motion ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Flow Physics

Seamless advancements in electronics industry resulted in high performance computing. These innovations lead to smaller electronics systems with higher heat fluxes than ever. However, shrinking nature of real estate for thermal management has created a need for more effective and compact cooling solutions. Novel cooling techniques have been of interest to solve the demand. One such technology that functions with the principle of creating vortex rings is called synthetic jets. The jets are meso-scale devices operating as zero-net-mass-flux principle by ingesting and ejection of high velocity working fluid from a single opening. These devices produce periodic jet streams, which may have peak velocities over 20 times greater than conventional, comparable size fan velocities. Those jets enhance heat transfer in both natural and forced convection significantly over bare and extended surfaces. Recognizing the heat transfer physics over surfaces require a fundamental understanding of the flow physics caused by micro fluid motion. A comprehensive computational and experimental study has been performed to understand the flow physics of a synthetic jet. Computational study has been performed via Fluent commercial software, while the experimental study has been performed by using Laser Doppler Anemometry. Since synthetic jets are typical sine-wave excited between 20 and 60 V range, they have an orifice peak velocity of over 60 m/s, resulting in a Reynolds number of 2000. CFD predictions on the vortex dipole location fall within 10% of the experimental measurement uncertainty band.

A Computational and Experimental Investigation of Synthetic Jets for Cooling of Electronics

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Mehmet Arik ◽  
Yogen V. Utturkar
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
High Performance ◽  
Laser Doppler Anemometry ◽  
Computational Study ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Flow Physics

Seamless advancements in electronics industry resulted in high performance computing. These innovations lead to smaller electronics systems with higher heat fluxes than ever. However, shrinking nature of real estate for thermal management has created a need for more effective and compact cooling solutions. Novel cooling techniques have been of interest to solve the demand. One such technology that functions with the principle of creating vortex rings is called synthetic jets. These jets are mesoscale devices operating as zero-net-mass-flux principle by ingesting and ejection of high velocity working fluid from a single opening. These devices produce periodic jet streams, which may have peak velocities over 20 times greater than conventional, comparable size fan velocities. These jets enhance heat transfer in both natural and forced convection significantly over bare and extended surfaces. Recognizing the heat transfer physics over surfaces require a fundamental understanding of the flow physics caused by microfluid motion. A comprehensive computational and experimental study has been performed to understand the flow physics of a synthetic jet. Computational study has been performed via FLUENT commercial software, while the experimental study has been performed by using laser Doppler anemometry (LDA). Since synthetic jets are typical sine-wave excited between 20 and 60 V range, they have an orifice peak velocity of over 60 m/s, resulting in a Reynolds number of over 2000. Computational fluid dynamics (CFD) predictions on the vortex dipole location fall within 10% of the experimental measurement uncertainty band.

Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

1995 ◽  
Vol 53 ◽  
pp. 636-637
Author(s):  
Norio Baba ◽  
Norihiko Ichise ◽  
Syunya Watanabe
Keyword(s):  
Experimental Study ◽  
Spherical Aberration ◽  
Incident Beam ◽  
Optical Parameters ◽  
Beam Tilting ◽  
Illumination Method ◽  
Restoration Method ◽  
Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

Sign in / Sign up

Export Citation Format

Share Document